1. Field of the Invention
The invention relates to paperboard, corrugated or similar cartons and containers, made in an automated manner by folding panels of an integral flat blank and gluing the panels at key locations including gusset corner joints. Each gusset corner joint has a back fold glued to one of side or end panels, and erects one of panels (e.g., a side panel) when the adjacent panel (e.g., an end panel) is lifted perpendicular to the bottom from a knocked down flat configuration of the folded/glued blank.
The container is optimized for shopping access, particularly for warehouse-type retail establishments in which products are sold from containers stacked on pallets. Cutouts for manual access to the contents are provided in each of the four side and end panels of the container. The cutouts are spaced inwardly from the corners, leaving panels forming wall portions that meet at the corners. At least at one of the panels at each gusset corner joint, a vertical-reinforcing structure having at least two glued thicknesses of material is folded inwardly and encloses over the associated gusset corner joint. The vertical-reinforcing structure has oppositely directed lock tabs, one attaching the reinforcing structure to the bottom and the other protruding upwardly to engage a container stacked atop the first container. By locking over the gusset corner joint, the container is held in a rectilinear erected shape. The structural integrity of the container against bending or warping of its rectilinear shape is further maintained by edge fold-in panels at each cutout, which also fold inwardly and tab lock into the bottom.
2. Related Art
Corrugated and paperboard containers are made from one or more pieces of flat stock that are cut in required shapes and are assembled to form the walls of a full or partial enclosure. Variations are possible in which several separately-integral parts are formed and then are assembled using glue, tape, staples or the like. For example, the container body and lid may be separate parts, or various types of inserts may be used for reinforcement or other purposes, such as subdividing the volume of the container into discrete areas.
Containers are supplied in a collapsed state because storage or handling of empty containers is wasteful of space. The containers are partly formed, with their parts cut out and certain seams and folds provided. The packer erects the containers prior to loading, and finishes any required assembly steps in the process. The loaded containers may be closed for storage or shipment by a lid formed from integral flaps or a separate piece, as suitable for storage or shipment. For example, a container may be cut out from integral flat stock, folded and scored at spaced parallel lines corresponding to the corners of the container (with at least one seam), and supplied with the opposite side and end walls collapsed flat against one another. Top and bottom flaps are likewise integrally attached to the side and end walls at folds or score lines. The packer erects the container from a flat parallelogram into its rectilinear shape, folding the bottom and top flaps inwardly before and after loading, respectively, and finally closing the container at seams that are taped, glued or otherwise attached.
It is efficient if most or all of the container parts are integral parts and extensions of a single piece of flat material. Separate discrete parts such as separate lids, partitions and reinforcing inserts involve manual assembly steps. Manual assembly steps are costly and consume worker time in several ways. In addition, assembly steps can be physically taxing and may lead to repetitive motion injuries. It is preferable if containers are substantially fully formed when supplied, and require the least possible manual action to deploy, load, close and store or pack the containers for shipment. However it is also important for the containers to be structurally sound.
Cartons or containers formed from paperboard, corrugated craft or similar flat sheet stock material are often stacked on one another during shipping and storage of products. In high volume retail stores, product is not only stored in stacked corrugated cartons, but frequently is presented to consumers in that form, for example with the cartons stacked on pallets. Stacking is obviously efficient as to the use of space, and storing a large quantity of product at a location accessible to the retail purchasers reduces the frequency of restocking. Pallets also enable a number of cartons to be handled efficiently as a unit.
The uppermost remaining carton on a pallet can be opened by removal of its lid. Consumers reach into the packing/shipping carton and withdraw product that is packaged in smaller units. When the cartons on the uppermost level are empty, they are removed and the next lower cartons are opened. It is possible to provide a tear-out opening in the side walls of a carton to facilitate access to the product therein. The tear-out panel provides structural support for the carton and protects the product, until the panel is torn out, normally at perforations defining a window spaced from the comers of the carton, to allow access.
Removal of the tear-out panel removes a substantial part of the structural support for the carton. Therefore, such panels are not removed until a carton is at the stage where consumer access is needed (e.g., on top of a stack). If a carton with a removed tear-out panel is subjected to vertical compression force, for example as occurs in stacking on a pallet, there is a tendency for the end walls of the carton adjacent to the tear-out panel to collapse inwardly toward one another or to splay outwardly because the tear-out panel is not in place to bear compression and tension loads.
Stacked cartons can have protruding tabs that engage in corresponding openings in adjacent cartons such that the cartons are stacked in registry. Stacking tabs help to maintain the integrity of a stack because the vertical walls of stacked cartons are kept in vertical alignment, defining columns in which the vertical walls of each carton are aligned with the corresponding vertical walls of other cartons for bearing vertical compression force. However, even cartons stacked in registry are subject to collapse by their opposite vertical walls becoming diverted inwardly toward one another or splayed outwardly, particularly if the material between such walls is removed by a gap or tear-out panel.
Containers in stacks are subjected to various forces, not limited to vertical compression due to the weight of containers over them in a stack. Such forces (as well as vertical compressive forces) are aggravated by handling, for example transport of a stack on a pallet, manual handling of one or more containers in a stack, etc. Tension and/or compression applied in various directions to the container walls can be sufficient to wholly or partly collapse a container or laterally to deflect, bend or fold the vertically oriented walls of the container. The result is a reduction of structural integrity, and may include crushing or other damage to the container contents. In addition, when the walls of one or more containers in a stack are crushed, wholly or partly collapsed, or otherwise deformed, the deformed container may no longer provide a stable horizontal support for containers stacked over it. The overlying stack may then tip laterally. A leaning xe2x80x9ctowerxe2x80x9d of containers may fall, and even if there is no injury to persons, the contents of the containers may spill or be damaged.
Shipping and retail display cartons having means for improving access to the product in the container are disclosed in U.S. Pat. Nos. 5,839,650 and 5,413,276xe2x80x94Sheffer, which are hereby incorporated. The carton is cut, glued and folded from a flat blank. Sidewall openings are provided such that the customer can reach into the carton from the front or from the top when the carton is opened. The sidewall openings are covered by flaps attached to top panels of the carton such that the openings are uncovered when the top is removed. Two sidewall openings are provided in the same front sidewall, leaving a web of the sidewall between them, which is supported by an internal wall spanning from the back wall to the web at the front wall, to which the internal wall is attached. This carton is apt for pallet displays and the like because it provides protection and support during shipping and access to the product when opened. However once opened, the carton is prone to collapse because the gaps or sidewall openings provided for access reduce the vertical stacking strength of the carton.
Use of pallets of shipping/display containers for storage and display of product at the customer level heightens problems with total or partial collapse of the containers or stacks of containers. For example, in addition to handling by retail/warehouse personnel typically associated with pallets of containers, multiple potential customers have access to and perhaps manipulate stacked containers. Crushed or damaged containers, and merchandise in the containers, are immediately visible to potential customers, reducing the appeal of the product and potentially damaging the reputation of the warehouse retailer or other seller. Falling xe2x80x9ctowersxe2x80x9d of containers and spilled product may disrupt traffic flow, startle customers or cause injuries by virtue of impact or consequential slip and fall incidents.
Apart from instability due to partial collapse of the walls of one or more containers in a stack, instability leading to spills and possible collapse of a stack may be caused by containers being shifted horizontally relative to underlying containers. Customer access and traffic in retail/warehouse stores makes it likely that containers will be shifted horizontally.
Self-erecting paperboard and corrugated containers are known with their respective wall panels and flaps connected in such a way that one or more of the structural parts of the container is pulled into an erected position as the other parts are erected. Commonly owned pending patent application Ser. No. 09/129,375, filed Aug. 5, 1998, entitled Stackable Container, discloses an integral blank container having folded and glued bellows or gusset corners that couple a bottom panel with side and end wall panels. When the container is erected from the knocked-down-flat state, the assembler need only pull on (or otherwise relatively displace) one of the panels, which pulls all of the panels into a rectilinear shape. In another commonly owned pending patent application Ser. No. 09/253,822, filed Feb. 19, 1999, an integral blank container including end walls with spaced inner and outer end wall panels and an upper/edge is disclosed. Advantageously, the end wall panels and ledge encompass hollow erectable support columns that are associated with upwardly protruding stacking tabs. The internal hollow columns, which are supported by folded and glued panels and are opened under the ledge when the container is in an erected state, vertically reinforce the end walls of the container.
U.S. Pat. No. 4,899,929xe2x80x94Grollman, discloses self-erecting bottom flaps connected to container side walls by folded-back glued gusset panels. The gusset panels are arranged to pull the bottom flaps downwardly into a position perpendicular to the side walls when the side and end walls are unfolded from one another during manual expansion of the container from a flattened parallelogram into a rectilinear box.
The foregoing applications include locking tab structures in which a plural thickness tab protrudes upwardly from the structure of the container end wall to engage in an opening in a similar container stacked thereon. One objective of cartons or containers as described is to support the products that have been loaded into the containers, as well as to bear the load of additional containers that may be stacked on a given container. For this purpose, the panels that are folded and glued can include wall panels having multiple thicknesses of glued-together material and/or partition walls that extend between opposite side walls or end walls. These structural reinforcing features add to the vertical stacking strength or load bearing capacity of the container, namely the maximum vertical weight that can be borne without buckling or displacing the container walls. However, the structures added for vertical stacking strength tend to preclude locating a consumer-access gap or sidewall opening in the same location.
What is needed is an optimal carton that provides good access to the product in the carton as well as good vertical stacking strength and vertical self-alignment features.
The present invention, as in the Sheffer pending applications, provides a site-erected container or carton that is at least substantially formed from a folded and glued, knocked-down-flat blank made from an integral flat sheet. Upon erection of the container into a rectilinear shape from the knocked-down-flat configuration, by means of self-erecting gusset corner joints, extensions of the end walls are folded inwardly to enclose around the gusset joints and to lock into the bottom panel. Each of the four corners of the carton is provided with at least one inwardly folded extension, and the extensions are spaced by deep gaps in the associated walls, provided to facilitate customer access.
The end and side walls are simultaneously erected perpendicular to the bottom panel. The gusset panels are compressed and held by the folded-in extensions of the end panel, which holds the container in a rectilinear shape. The end walls are provided with registry tabs on a stacking ledge having a thickness equal to the number of material thickness that are provided in the outer wall panel, glued in the gusset joint, and folded over. In a preferred embodiment, five thicknesses of material are provided to reinforce the container. The container is supplied with substantially all its joints pre-attached but in a knocked-down-flat state.
Preferably, each of the four opposite side and end walls is provided with an opening spaced from the carton corners where such wall is integral with two adjacent walls. At least those walls where the gusset joints are folded flat have folded-in extensions of the end walls. Each of the openings preferably includes a reinforcing edge flap that is folded inwardly from the lower edge of the opening along at least one fold line, and locks into the bottom of the carton. Thus the thickness of the associated wall is at least doubled at the point where the vertical extension of the wall is at a minimum due to the customer access opening. Thus four access openings are provided, the corners are reinforced for vertical stacking and the whole carton is held in a rectilinear shape. For further support and also to subdivide the internal volume of the carton into areas separately associated with each access opening, an X-shaped divider can be coupled into the sidewalls adjacent to the reinforcing folded over panels.
The container can be produced automatically using a fold-and-glue container production machine, for example as available from Bobst Group, Inc., 146 Harrison Avenue, Roseland, N.J. 07068 (affiliated with Bobst, S A, Lausanne, C H). At the loading site the user need only fold the end panels into place, place and lock down the X-shaped internal divider by placing it and folding over the reinforcing panels, and fill the container. The container can be stacked, stored and shipped without attention to tear-out panels, and yet provides very good customer access and has robust structural strength.
It is an object of the invention to structure a fold-and-glue knocked-down flat container blank so as to provide side and/or end wall openings for customer access without giving up substantial structural strength for vertical stacking and for holding a rectilinear shape in the erected container.
It is another object both to structure the opposite end walls of a container for good stacking strength, including by providing multiple thickness column-like corner structures, and to improve the rectilinear shape of the container and its tendency to stack in registry.
It is an object to deploy a protruding registry tab and to provide a corresponding tab receptacle for stacking cartons, on reinforcing end wall flaps.
These and other objects are accomplished by a preferably one-piece fold-and-glue container with corners reinforced by extensions that fold over and compress self-erecting bellows or gusset corner joints, and cutouts in each of the four front, back and end walls. The corrugated paperboard panels of a single flat blank define a bottom, opposite front and back walls and longitudinally opposite end walls. The joints have bellows panels integral with the front, back and end walls, joined at folds oriented diagonally and being glued to one of the adjacent walls to pull one another perpendicular to the bottom when erected. The end walls have an outer end wall panel integrally extending from the bottom and joined adjacent to the front or back to an extension having a protruding tab at its free end for locking into the bottom when the extension is folded over the gusset joint. The cutout in each wall is spaced inwardly from opposite ends and extends only part way from a top edge to the bottom, leaving a lower wall portion adjacent to the bottom at which the material is doubled over and also locked to the bottom. Adjacent to the junction between the extension and the outer end wall, a registration tab is cut in the extension to register with a corresponding opening in the bottom of a container stacked on the container. The extensions can have two or more thicknesses of material folded laterally inward and glued against one another for added reinforcement.